435
FXUS63 KGRR 011134
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
634 AM EST SAT FEB 1 2025
KEY MESSAGES
- LIGHT SNOW SUNDAY AND MONDAY
- WINTRY MIX MID WEEK
DISCUSSION
ISSUED AT 310 AM EST SAT FEB 1 2025
- LIGHT SNOW SUNDAY
LOW PRESSURE IS GOING TO MOVE ACROSS SOUTHERN CANADA DURING THE
NEXT 30 HOURS AND WE ARE GOING TO BE AFFECTED BY PRECIPITATION
THAT DEVELOPS IN THE WARM ADVECTION WING OF THIS CYCLONE.
LIGHT SNOW IS EXPECTED TO DEVELOP OVER THE UPPER MS VALLEY LATER
THIS EVENING AS ISENTROPIC LIFT ON THE 290K SURFACE SATURATES THE
COLUMN ALONG THE WARM FRONT. FORECAST SOUNDINGS SHOW THE PROFILE
SATURATED UP THROUGH 600MB AND WELL BELOW 0C. HOWEVER, THERE IS A
WARM NOSE NOTED NEAR 850 MB THAT NUDGES UP TO OR JUST OVER THE 0C
LINE OVER THE SOUTHERN CWA AFTER 12Z. FOR MOST OF THE CWA, THIS
WILL BE A LIGHT SNOW EVENT WITH 1-3 INCHES NORTH OF I-96 AND
AROUND A HALF INCH SOUTH OF THERE. ADDITIONALLY, SOUTH OF I-96,
THE SNOW MAY MIX WITH SOME FREEZING RAIN SUNDAY MORNING, BUT THE
WINDOW FOR THAT HAPPENING IS ONLY A COUPLE OF HOURS BEFORE SURFACE
TEMPERATURES RISE ABOVE FREEZING. ENSEMBLE PROBABILITIES POINT
TOWARD A 25 PERCENT CHANCE OF LIGHT FREEZING RAIN ALONG THE I-94
CORRIDOR SUNDAY MORNING. THE PRECIPITATION WILL MOVE EAST OF THE
CWA BY 00Z.
A BRIEF PERIOD OF LIGHT SNOW IS ALSO POSSIBLE MONDAY AS A FLEETING
SHORT WAVE RACES ACROSS THE UPPER MIDWEST AND THE CWA ALONG THE
TRAILING COLD FRONT FROM TONIGHT'S SYSTEM. LOW CHANCES FOR
FREEZING RAIN EXIST WITH THIS SYSTEM BUT THE MOSTLY LIKELY P-TYPE
IS LIGHT SNOW. ACCUMS AROUND A HALF INCH ARE POSSIBLE NORTH OF
I-96.
- WINTRY MIX MID WEEK
WE'VE BEEN WATCHING THE EVOLUTION OF THE NEXT SYSTEM FOR A FEW
DAYS AND THERE HAVEN'T BEEN TOO MANY CHANGES YET.
A SOUTHERN STREAM WAVE WILL INDUCE A SURFACE LOW IN THE LEE OF THE
ROCKIES TUESDAY NIGHT AND THEN MOVE NORTHEAST TOWARD THE SOUTHERN
GREAT LAKES BY WEDNESDAY. THE ECMWF IS FARTHER WEST AND DEEPER
THAN THE GFS IS AND SO GIVES A BIT MORE IN THE WAY OF FREEZING
RAIN. ENSEMBLE PROBABILITIES POINT TOWARD A 50-60 PERCENT CHANCE
OF FREEZING RAIN WEDNESDAY SOUTH OF M-46, WITH HIGHEST
PROBABILITIES ALONG THE I-94 CORRIDOR. AT THIS POINT, ENSEMBLES
INDICATE A 20 PERCENT CHANCE OF A TENTH OF AN INCH OF ICE
ACCUMULATION; MOSTLY LIKELY ICE ACCUMS WILL BE HALF OF THAT.
THERE WILL PROBABILITY BE A MIX WITH AND CHANGEOVER TO RAIN ACROSS
THE SOUTHERN CWA DURING THE DAY AND SOME SNOW MIXED IN ACROSS THE
NORTH. WE'LL CONTINUE TO MONITOR THE EVOLUTION OF THIS SYSTEM AS
IT HAS THE POTENTIAL TO RESULT IN HAZARDOUS TRAVEL. PRECIPITATION
WITH THIS SYSTEM WILL LINGER INTO EARLY THURSDAY BEFORE MOVING
EAST.
AVIATION /12Z TAFS THROUGH 12Z SUNDAY/
ISSUED AT 634 AM EST SAT FEB 1 2025
VFR CONDITIONS ARE EXPECTED THROUGHOUT THE DAY. MKG MAY DROP TO
MVFR WITH CEILINGS AROUND 3000 FEET THIS MORNING. OTHERWISE FEW-
SCT 3000 CLOUDS WILL BE PRESENT THIS MORNING WITH WINDS GRADUALLY
TURNING TO THE SOUTHEAST THROUGHOUT THE DAY. LATE TONIGHT LIGHT SNOW
MOVES IN FROM THE WEST INTO SUNDAY MORNING. CEILINGS WILL DROP
TO MVFR AND THEN IFR WITH THE SNOW. SNOW WILL ALSO CAUSE
VISIBILITIES TO DROP TO 1 TO 4 SM FOR MOST WITH BRIEF PERIODS OF
LESS THAN 1 SM POSSIBLE.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST THIS MORNING FOR LMZ844-845-
848-849.
DISCUSSION...04
AVIATION...RAH
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